(define (my-map p sequence)
  (accumulate (lambda (x y) (cons (p x) y))
              '()
              sequence))

(define (append seq1 seq2)
  (accumulate cons seq2 seq1))

(define (length sequence)
  (accumulate (lambda (first already-acc)
                (+ 1 already-acc))
              0 
              sequence))
